“Our 2012 season was disappointing for many reasons,” general manager Ben Cherington said in the team’s announcement. “No single issue is the reason, and no single individual is to blame. We’ve been making personnel changes since August, and we will continue to do so as we build a contending club. With an historic number of injuries, Bobby was dealt a difficult hand. He did the best he could under seriously adverse circumstances, and I am thankful to him.”

The Sox finished 69-93, their worst record since 1965, and finished in last place in the American League East for the first time since John Henry and Tom Werner became owners 11 years ago.

“I’m disappointed, yeah,” Valentine said in an impromptu meeting with reporters after he first eluded them as he started a bike ride Thursday afternoon. “This is not the press conference that I was expecting at the end of the season.”

Not since 1934 had the Red Sox fired a manager after only one season. But the 62-year-old Valentine was a controversial choice to replace Terry Francona, and his tenure proved rocky.

“A lot of things didn’t go well, but an experienced manager is supposed to put his finger in the dike and keep the water on the other side,” he said.

Valentine was not the choice of first-year general manager Ben Cherington. Team president/CEO Larry Lucchino engineered the deal after the Red Sox interviewed five other candidates, believing Valentine would restore order to a team that tuned out Francona and collapsed down the stretch in 2011.

“I understand this decision,” Valentine said in the team press release. “This year in Boston has been an incredible experience for me, but I am as disappointed in the results as are ownership and the great fans of Red Sox Nation. It was a privilege to be part of the 100 year anniversary of Fenway Park and an honor to be in uniform with such great players and coaches. My best to the organization. I’m sure next year will be a turnaround year.”

But the situation grew worse. Valentine had almost no allies within the organization beyond Lucchino and a handful of players.

“This year’s won-loss record reflects a season of agony,” Red Sox CEO Larry Lucchino said. “It begs for changes, some of which have already transpired. More will come. We are determined to fix that which is broken and return the Red Sox to the level of success we have experienced over the past decade. Difficult as it is to judge a manager amid a season that had an epidemic of injuries, we feel we need to make changes. Bobby leaves the Red Sox’ manager’s office with our respect, gratitude, and affection. I have no doubt that he will continue to contribute to the game he loves so much and knows so well.”

Valentine was urged to retain three of the assistant coaches and to hire Bob McClure as the pitching coach. Before the end of spring training, Valentine was at odds with McClure, bench coach Tim Bogar, and bullpen coach Gary Tuck.

Within a few months, Valentine would go days without speaking more than a few words to some of his coaches. McClure, whose hands-off style helped lead to the Red Sox having one of the worst rotations in the game, was eventually fired in August.

Valentine’s relationship with the players started to sour in April when he questioned the commitment of third baseman Kevin Youkilis by saying, “I don’t think he’s as physically or emotionally into the game as he has been in the past for some reason.”

Cherington forced Valentine to apologize to Youkilis, and second baseman Dustin Pedroia dismissively said that criticizing players wasn’t how the Red Sox went about their business.

As injuries mounted and the team became progressively worse, Valentine’s relationship with the players became more distant. It was a clash of styles more than personalities.

Valentine favored the idea of having an open-door policy. If a player had a problem, he should come talk to him. The players had become accustomed to Francona coming to them.

Francona also used his coaches as conduits to the clubhouse, something Valentine was unable to do because of their loyalty to the front office.

All too often, the Red Sox appeared disorganized, if not unprepared. The chasm between the manager’s office and the rest of the baseball operations staff was a wide one.

In July, a group of mutinous players contacted Henry and Werner and demanded a meeting in New York during a road trip. Despite their complaints about Valentine, he stayed on the job.

Valentine also tangled with the media, often mocking questions or answering them frivolously. When radio host Glenn Ordway asked Valentine whether he had “checked out” on the season, the manager threatened to punch him. It was a joke, he said.

But the controversies, many of them contrived, were not why the Red Sox lost so many games.

They had 27 players, 13 of them former All-Stars, go on the disabled list a franchise-record 34 times. In all, the Sox had 1,495 games missed because of injuries. Valentine never once managed a game with a full complement of the team’s best players.

Valentine also was saddled with a poor rotation, Red Sox starters posting an ERA of 5.15. Bad decisions made before he was hired, including turning ace reliever Daniel Bard into a starter, worked against him.

Injuries to David Ortiz and Will Middlebrooks helped put the team out of contention in August. On Aug. 25, the Red Sox hit the reset button on their franchise with a landmark trade that sent righthander Josh Beckett, outfielder Carl Crawford, and first baseman Adrian Gonzalez to the Dodgers.

The Red Sox received five players in return and $264 million in long-term payroll savings. Valentine was left with a roster full of minor leaguers, and the Red Sox lost games in bunches through the end of the season.

Now the pressure will fall squarely on Cherington to use the financial flexibility gained in the Dodgers trade to reverse the fortunes of a team that has plunged to the bottom of the American League.

The Red Sox have missed the playoffs for three seasons in a row and have not won a playoff game since 2008. Eighteen teams in the majors have qualified for the postseason since the Red Sox last did.

The Red Sox will start 2013 with their third manager in as many years. To end that George Steinbrenner-like disarray, the next choice must be a good one.

John Farrell, who has had a rocky two seasons as Toronto’s manager after spending five years as Red Sox pitching coach, may be the team’s first choice if the Blue Jays are willing to let him go.

Bogar could get the job after helping to push Valentine out the door. Or the Sox could conduct yet another search and bring a group of candidates to Fenway Park.

A quick decision is paramount. The Red Sox went two months without a manager last season and that backfired. There’s a lot of work to be done, and whoever takes on Boston’s most demanding job needs to get started.